code: def plot_polynomial(expr):
      """Plots the polynomial using the functions written in
      plotting module which in turn uses matplotlib backend.
  
      Parameter
      =========
  
      expr:
          Denotes a polynomial(SymPy expression).
      """
      from sympy.plotting.plot import plot3d, plot
  
      gens = expr.free_symbols
      if len(gens) == 2:
          plot3d(expr)
      else:
          plot(expr)
  
imports: from functools import cmp_to_key
  from sympy.abc import x, y, z
  from sympy.core import S, diff, Expr, Symbol
  from sympy.core.sympify import _sympify
  from sympy.geometry import Segment2D, Polygon, Point, Point2D
  from sympy.polys.polytools import LC, gcd_list, degree_list, Poly
  from sympy.simplify.simplify import nsimplify
label_desc: Use image node_id 23 for calling a global function with example usage: plot_polynomial(expr) without return types